Metal mold for molding hollow article having inwardly tapered side wall

Abstract

In a metal mold for molding a hollow product having inwardly tapered side wall with a stationary die plate for forming a bottom portion of the product, a core, and a cavity plate surrounding the core, the core has a truncated pyramid shape and first and second slide cores are provided between the core and the cavity plate. The core and slide cores are constructed such that at the time of opening the mold both slide cores are moved inwardly in an interlocked relation with retractive movement of the core thus leaving one end of the molded product for enabling removal thereof.

I claim: 
     
       1. A metal mold for molding a hollow product having a narrow opening, a wide bottom plate and a side wall between said narrow opening and said bottom plate, said metal mold comprising: a stationary mold plate secured to a stationary mounting plate of an injection molding machine and provided with a resin inlet runner for molding said bottom plate;   a movable cavity plate which is brought into contact with said stationary mold plate when said metal mold is closed and separated therefrom when said metal mold is opened;   means for moving said cavity plate in an axial direction of said mold over a stroke sufficient to remove a molded product from said stationary mold plate;   first and second pins secured to said movable cavity plate and oppositely inclined with respect to an axis of said mold;   a core to be located inside of said molded product and secured to a movable die plate of said injection molding machine, said core having a plurality of axially extending polygonal surfaces surrounding the same;   first slide cores which when said mold is closed engage with said polygonal surface of said core to form a portion of a side wall of said molded product, whereas when said mold is opened, said first slide cores are guided by said first pin to move together with said core toward the center of said mold over a stroke sufficient to remove said molded product in the axial direction and also to move in the radial direction;   first dove tail means disposed between one end of said first slide cores and said movable die plate and extending in a direction perpendicular to the axis of said core;   first and second cotters respectively having inclined surfaces parallel to said inclined polygonal surfaces;   second slide cores disposed adjacent said polygonal surfaces of said core, said second slide cores molding another portion of said side wall of said molded product together with said first slide cores when said mold is closed, said second and first slide cores being alternately arranged about said core, said first cotters being secured to said second slide cores, the inclined surfaces of said second cotters being caused to engage the inclined surfaces of said first cotters by said second pin when said mold is closed so as to urge said second slide core against said polygonal surfaces of said core; and   second dove tail means disposed between one end of said second slide cores and said movable die plate and extending in a direction perpendicular to the axis of said core, said first and second dove tail means limiting axial movements of said first and second slide cores while guiding their radial movements.